Fountain pen



2 Sheets-Sheet 2 INVENTOR. fif/V/Vff/f 00A 15 FOUNTAIN PEN Filecl. arch16. 1939 Patentedl Apr. 15, 1941 iJNlTED STTS A'ENT OFFICE FOUNTAIN PENKenneth Dole, Melrose, Mass. Application March 16, 1939, Serial No.262,163

6 Claims.

This invention relates to fountain pens of the type adapted to be filledby operation of an elastic pump usually in the form of a rubber tube orsac located within the barrel of the pen and operated by twisting tofill or empty the pen.

This application is a continuation in part of my prior applicationSerial No. 248,159, filed December 29, 1938.

The principal object of the invention is to provide a simple,inexpensive, and durable pen of the above character wherein the rubberpump will operate with ease and efiiciency, and in which the lengthwisefolds resulting from twisting will not bulge the body of the tube to anyconsiderable extent or cause chafing against the surrounding inner wallof the pen-barrel.

This desirable result is attained by so constructing the rubber tubethat it will fold along a number of predetermined lines lengthwiseduring twisting, with assurance that the rubber will automatically formitself into proper shape, both lengthwise and circumferentially, toclear the inner wall of the pen barrel. Formerly in rubber pumps of thistype the indiscriminate folds resulting from twisting causedconsiderable friction against the pen barrel and gave much annoyance dueto delayed pumping action.

A pump tube incorporating the foregoing features of improvement may bemolded or otherwise formed from suitable elastic material so as toprovide, for instance, three lengthwise gen erally diagonal ribs or setsof narrow channels equally spaced apart around the inner periphery ofthe tube. These ribs or channels cause the tube to fold or crease alongthree well defined lines spirally of the pump body when twisted. Thetwisted wall of the rubber body consequently rearranges itself adjacentthe crease lines and shows in cross-section three folds or ridgesspirally along the wall of the tube, and with the rubber crowded inwardtoward the axis to exhaust the tube prior to filling.

The present pump tube is intended to overcome the faults of thefiller-tube or sac in previous twist-filler pens. These faults have allarisen from the fact that an elastic tube when twisted winds up normallywith two folds, flattening out and bulging at the beginning of thetwist, and then turning over on itself and collapsing. A tube onequarter of an inch in diameter, for example, bulges as much as asixteenth of an inch at each of the two folds, or a total of an eighthof an inch. This bulging necessitates either allowing the tube to rubagainst the wall of the barrel, or the use of such a small tube as toreduce the ink capacity of the pen considerably and make the pumping sodifficult as to require many twists to fill the pen. Owing to the demandfor large capacity pens, manufacturers have had no choice except toemploy a tube large enough to pump efficiently and fill the pen quickly,even though rubbing against the pen barrel was inevitable. In somecases, a shorter, less efficient pumping tube has been used in anattempt to solve the difficulty, but without satisfactory results.

The various features and constructional details of the present inventionwhich overcome the foregoing difficulties will apear as the descriptionproceeds, reference being made to the accompanying drawings in which:

Figure l is a lengthwise section through a pen embodying the improvedrubber pump of this invention,

Figure 2, a lengthwise section of one form of pump tube,

Figure 3, a cross-section on the line 3--3 of Figure 2,

Figure i, a lengthwise sectional view of another form of pump tube,

Figure 5, a cross-section on the line 55 of Figure 4.,

Figure 6 illustrates one line of curvature the ribs or channels mayfollow,

Figure '7, another such line,

Figures 8 and 9, cross-sections of the twisted tubes respectively ofFigures 2 and 4,

Figure 10, another similar form of pen construction, and

Figures 11 and 12, a side view and section of another tube.

The improved filling pump of this invention may be incorporated in anysuitable form of pen construction employing means for twisting therubber tube about its axis to cause folding and unfolding of the rubberwall.

For the purpose of illustration, the pen is shown in the drawings asincluding a body I which may be made in two sections shown as barrelsection 2 and reservoir section 3 joined together at the point 4, thesection 3 being formed to provide a nipple or reduced portion 5 and ashoulder B.

The writing end of the pen is provided with a stock 1 threaded at 8 intothe outer end 9 of the section 3 and holding a nib Ill. The other end ofthe pen carries a turning knob ll loosely threaded at [2 into the end ofthe section 2.

For filling andemptying the pen there is provided an elastic pumpingelement, preferably in the form of a rubber tube l4, enclosed within theinner wall l5 of the barrel section 2, the upper end It of the tubebeing held tightly within a circular cavity ll of the turning knob by aninternal bushing I8, while the lower end IQ of the tube is held tightlybetween the nipple 5 and the inner wall portion 23 of the barrel section2. Rotation of the turning knob ll results in a twisting of the tube idto pump ink into the pen through the channel 21. An air-vent tube 22mounted in a feed-bar 23 extends along the interior of the pen and hasan opening 24 communicating with the channel 2|. The other end of thevent-tube terminates within the hollow turning knob, leaving a slightclearance between the end of the vent-tube and the inner face 25 of theturning knob. Suitable clearance is provided at 26 between the vent-tubeand the nipple 5, and also at 2'! between the venttube and the bushingl8. In order to insure proper folding, when twisted, the rubber tube i lmay be formed with a series of internal, uniformly spaced, channels 28extending lengthwise in a helical curve such as indicated at 293 inFigures 2 and 3, wherein the lines of channels curve in one direction atone end, and in the other direction at the opposite end. These channelsestablish predetermined lines for the wall of the rubber tube to foldalong when twisted during the pumping operation set in action by theturning knob. In the example shown in the drawings, it is clear that thetube will form itself into three folds lengthwise of the tube, and thatthe rubber folds will present a substantially symmetrical contour freeof the inner wall I5 of the barrel section 2, (Figs. 8, 9) eliminatingany possibility of friction thereagainst. This is to be contrasted withprior constructions in which the folds assumed a flat or irregularcross-section during twisting, resulting in the disadvantages aboveenumerated.

Another example of construction resulting in controlled folding isillustrated in Figures 4 and 5, wherein the elastic tube M has a series(three) internal ribs 30 extending lengthwise of the tube in the samegeneral contour as described in connection with Figure 2. These ribspreferably take the form shown in cross-section in Figure 5,

in which an obtuse angle 3! is formed on one side I of a rib, and anacute angle 32 on the other side of the rib. The rubber wall may be madethinner at the sides of the ribs as indicated at 33.

It will also be noted that the walls of the tubes l4 and I4 are thinnerat the lower end l9 than at the other end, being tapered so that whentwisted, the tubes will wind upward, forcing the air, or ink and air,toward the top of the pen.

Rubber pump tubes of the improved kind as described herein, may beproduced by dipping specially shaped forms in latex, or by pouring latexinto suitable molds. There are three possible types of forms. If theform is dipped no more than twice, indentations along the lines offolding will produce a satisfactory tube. If dipped as many as fivetimes, a form for producing the tube illustrated in Figures 4 and 5 maybe used. Such a form will have three deep grooves, each having an acuteedge and an obtuse edge along the lines of folding. The edges are thesame distance apart as the creases to be formed in the finished tube.

In producing this tube by the dipping process, the latex flows when theform has been lifted from the dipping bath, down across the obtuse edgeinto the groove, then down toward the bottom of the form, and a certainamount out of the groove across the acute edge. The line of thin rubberresults as indicated at 33 along the obtuse edge, and the line ofthinner rubber 33' along the acute edge. Since the outer crease in afold tends to turn before the inner crease, the fold can be made to lapin the right direction by having the outer crease made of slightlythinner rubber than the inner crease, and by having the acute edge ofthe groove on the proper side for the outer crease. This is importantfor the reason that if the fold lapped over in the wrong direction itwould merely become part of the fold next to it, and the tube would windup with two folds resulting in bulging.

Probably more essential than having one crease thinner than the other inmaking the folds lap over in the right direction, is having the foldsfollow the right line of curve. Ordinarily a fold laps over in thedirection the tube is twisted, at the end it is twisted, and in theother direction at the other end. If it is twisted counter-clockwise,for example, it will lap over counter-clockwise at the end it is twistedand clockwise at the other end. This results in the fold standing up andbulging at the middle where it changes the direction of its lapping. Butif the fold follows the correct line of curve it will lap over in thesame direction all the way and lie flat. To make the fold lap over inthe direction it is twisted, the helical curve 29 is followed asexplained in connection with Figures 2 and 4 above. To make the fold lapover in the opposite direction, an arc of a circle is followed asindicated in Figure '7. The first curve is preferred because it conformswith the natural inclination of the rubber tube to fold over the way itis twisted.

If the tube is dipped more than five times, a third type of form is moresuitable. Instead of a grOOVe for making the creases, this form has apair of ridges. The rubber is thinner over the top of the ridges, andthe creases fold along the thin rubber.

In assembling the pen parts, the lower end of the tube I 4 or M iscemented on to the nipple 5 forming the upper end of section 3 which hasthe shoulder 6. Section 2 is then pressed on to section 3 tightly aboutthe lower end I9 of the tube. The bushing I8 is then inserted somedistance into the upper end [6 of the tube. A small amount of cement isbrushed over the surface of the cavity I! of the turning knob, and thelatter is then screwed on to section 2, with the upper end l6 of thetube entering it. A special tool is then used to force the bushing l8into place.

If the pen barrel is made of sheet material wound around a cylinder,rather than bored out of a solid rod, the nipple will comprise aseparate part held between the sections of the pen barrel, as will bereadily understood.

In the Figure 10 pen, the barrel 40 has internal threads 4| into whichthe threaded end 42 of the stock 43 is screwed. A feed-bar 44 holding anib .5 is located within a bore 46 of the stock 43.

The opposite end of the pen carries a turning knob il loosely threadedat 48 into the upper end of the barrel 4!] so as to be freely rotatabletherein. A tube support 49 at this end of the barrel is threaded into acavity 5!! of the turning knob 41, and is slightly reduced at 5| toreceive the upper end 52 of an elastic filling pump in the form of arubber tube 53. The lower end 54 of the rubber tube 53 is received on areduced portion 55 of an intermediate support 55 threaded at 51 into theslightly thicker portion 58 of the pen barrel. Both ends of the pumptube 53 may be cemented on to their respective supports and furtherreinforced by winding a few turns of silk or cotton over the ends.

The pump tube 53 preferably is tapered in crosssection, being thinnerand more pliant at its lower end M than at its upper end 52 which isthicker and less pliant, so that when the tube is twisted about itslongitudinal axis it twists from its lower end first, forcing the air orink to the upper part of the pen.

The pen barrel encloses a vent-tube 59 seated at one end within a cavity60 deep enough to insure that the tube at this end will not becomedisengaged when the knob 41 is turned to twist the rubber pump tube 53.The lower or other end 6| of the vent-tube 59 is held in a bore 62 inthe feedbar 44 and has a small opening 63 communicating with the inkchannel 64. A similar small opening 65 is located in the vent-tube atthe other end of the pen.

In order to insure proper folding of the rubber body of the filling tube53, the wall of the tube is shaped to provide indentations 66 or thinnedareas which predetermined the lines of folding to be developed in thetube when twisted about its axis. These indentations may be nine or anyother suitable number, there being three in a slanting row in thepresent example, so that the Y wall of the tube will fold along thethree lines defined by the slanting rows of indentations, which are thelines of least resistance, and will consequently fold in three definitefolds free from chafing against the pen barrel.

In all of the above noted pen constructions the pens are filled byturning the knobs back and forth in the well known manner, and thefilling operation is substantially as follows. During the first turn thepump tube Winds up on itself along the definite creases or fold lines asdescribed, causing the rubber wall to move inward toward the vent-tube,expelling the air within it through the upper part of the pen andthrough the opening 65, down through the vent-tube, into the opening 63and out of the pen through the ink channel 64.

In the first reverse turn, suction is created by the pump tube unwindingand returning to its original condition, and ink is drawn in through theink channel 64 and into the lower part of the barrel or reservoir.

During the second turn, air is similarly expelled, but at the same timea. certain amount of ink is forced out. Since the friction of airagainst the wall of a tube is less than the friction of a liquid, moreair may be forced through the ink channel 64 than ink. If the turningmovement is quick enough, not more than or drops of ink will beexpelled.

In the second reverse turn, as much ink will be drawn into the pen asduring the first turn, and, upon completion of the third pumping cyclethe pen will be full.

It is to be understood that the invention as set forth above is notconfined to the exact details of construction described, but may beotherwise embodied, or variously altered within the scope of theappended claims, and without departing from the fundamental principlesset forth in this specification. It is further to be understood that theexpression tubular cross-section as used in the claims is intended tomean all possible forms of rubber or elastic pump section in which anelastic wall creates a pumping effect when twisted, and whether suchsection is in an open tube, sac, or otherwise. Furthermore, thematerials of the pen may be varied as desired, and the lower end of thepen barrel, and the turning knob, or the entire pen body, may be madetransparent to allow view of the ink.

In conclusion it will be noted from a consideration of Figures 8 and 9that the pump walls collapse immediately along the predetermined foldlines on being twisted, thereby obviating the friction of priorconstructions, and facilitating the pumping action.

Having thus described my invention, I claim and desire to protect byLetters Patent:

1. A pump element for a fountain pen, comprising an elastic body oftubular cross-section provided with ribs arranged to cause the Wall ofsaid body to collapse with three or more lengthwise folds when twistedaxially, said wall being thinned along both sides of the ribs.

2. A pump element for a fountain pen comprising an elastic body oftubular cross section having a wall formed with equidistant pairs oflengthwise channels, one channel in each pair being deeper than theother.

3. A pump element for a fountain pen comprising an elastic body oftubular cross section having a wall formed with generally slanting linesof lengthwise indented areas, the wall being of the same thicknessthroughout.

4. A pump element for a fountain pen comprising an elastic body oftubular cross section, with a wall tapering in thickness from end toend, provided with equidistant pairs of lengthwise channels.

5. A pump element for a fountain pen comprising an elastic body oftubular cross-section capable of twisting, having a wall formed withpairs of internal, helical channels, each pair be-v ing an equaldistance from adjoining pairs, running lengthwise in the elastic bodyand having its middle section more on the line of the longitudinal planeof the body than its ends.

6. A pump element for a fountain pen comprising an elastic body oftubular cross-section capable of twisting, having a wall formed withpairs of internal channels, each pair being at an equal distance fromadjoining pairs, and with one end curving in the same direction as theother end.

KENNETH DOLE.

